
==== Front
Arch Orthop Trauma Surg
Arch Orthop Trauma Surg
Archives of Orthopaedic and Trauma Surgery
0936-8051
1434-3916
Springer Berlin Heidelberg Berlin/Heidelberg

39008074
5438
10.1007/s00402-024-05438-8
Knee Arthroplasty
Intra- and inter-operator reliability of three-dimensional preoperative planning in total knee arthroplasty
http://orcid.org/0000-0003-3997-1616
Cosendey Killian Killian.cosendey@chuv.ch

1
Moerenhout Kevin 1
Stanovici Julien 1
Jolles Brigitte M. 12
Favre Julien 13
1 https://ror.org/019whta54 grid.9851.5 0000 0001 2165 4204 Department of Musculoskeletal Medicine (DAL), Lausanne University Hospital and University of Lausanne (CHUV-UNIL), Avenue Pierre-Decker 4, Lausanne, CH-1005 Switzerland
2 https://ror.org/02s376052 grid.5333.6 0000 0001 2183 9049 Institute of Electrical and Micro Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
3 https://ror.org/01eas9a07 The Sense Innovation and Research Center, Lausanne & Sion, Switzerland
15 7 2024
15 7 2024
2024
144 8 36253630
5 12 2023
27 6 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by/4.0/ Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Purpose

To characterize the intra- and inter-operator reliability of a CT-based 3D preoperative planning software.

Materials and methods

This study analyzed 30 CT scans of de-identified knees with osteoarthritis. For each scan, a case planner segmented the bones and pre-planned the TKA. Three orthopedic surgeons then reviewed each pre-planning three times at least one week apart, in a blinded manner. During the reviews, the surgeons modified the pre-plannings until they felt the plannings matched the objectives defined collegially at the beginning of the study. Reliability was assessed using the Intraclass Correlation Coefficient (ICC) and the Standard Error of Measurement (SEM).

Results

The intra- and inter-operator reliabilities for implant size selection were almost perfect (ICC between 0.97 and 0.99). Implants of same sizes were selected in 67.1–90.0% of cases. For implant placements, almost perfect intra- and inter-operator reliability was observed in all degrees-of-freedom (ICC between 0.81 and 1.00), except in flexion-extension for the femur (intra-operator ICC between: 0.76 and 0.99; inter-operator ICC of 0.61) and the tibia (intra-operator ICC between 0.12 and 1.00; inter-operator ICC of 0.03). All implant placements SEM were below 1.3 mm or 1.7°.

Conclusions

This study showed high intra- and inter-operator reliability for implant size selection and, in most of the degrees-of-freedom, also for implant placements. Further research is needed to evaluate the benefit of developing more precise means of describing the objectives of the surgical planning as well as to evaluate the possibility and relevance of adding features in the planning software to assist the operators.

Keywords

Total knee arthroplasty
Preoperative planning
Reliability
Implant size selection
Implant placement
University of LausanneOpen access funding provided by University of Lausanne

issue-copyright-statement© Springer-Verlag GmbH Germany, part of Springer Nature 2024
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pmcIntroduction

Total Knee Arthroplasty (TKA) has become a common orthopedic procedure, with about 680’000 primary TKA surgeries performed each year in the United States [1]. Despite this large number, up to 18% of patients are unsatisfied with the function of their knee after TKA [2, 3]. Literature has related inappropriate size, malalignment, and misplacement of the implants to poorer outcomes [4, 5]. These findings highlight the importance of considering these factors carefully. They also encourage the development of means to improve their management.

Preoperative planning combined with assistive devices, such as robotic-assisted systems, computer navigations or patient-specific instrumentations, provides an opportunity to improve implant size selection, bone resection and implant placements [5–9]. In general, preoperative planning includes two phases: (1) an image acquisition phase, typically using magnetic resonance imaging (MRI) or computed tomography (CT) to determine the three-dimensional (3D) geometry of the knees and (2) a planning phase, consisting in segmenting the images to reconstruct 3D models of the patients’ bones, identifying bony landmarks, selecting the prosthesis model and size, and virtually placing the prosthesis on the 3D bone models. While preoperative planning is used worldwide, there has been limited research on this procedure.

The reliability of the implant size selection and of the implant placements in the planning software remain poorly documented. So far, one study analyzed the intra- and inter-operator reliability when planning primary TKA based on CT scan. It reported an excellent reliability for implant size (ICC range from 0.91 to 0.94), but moderate reliability for implant orientation (ICC range from 0.47 to 0.89) [10]. Another study using MRI for preoperative patient-specific instrumentation (PSI) planning observed an almost perfect intra- and inter-operator reliability for implant size (ICC range from 0.91 to 0.99), but the results were more heterogeneous for implant position (ICC range from 0.18 to 1.00) and orientation (ICC range from 0.08 to 1.00) [11]. These prior studies provide an interesting estimation. However, since many elements could influence the reliability results, such as the planning software, the surgical objectives, or the operators, there is a need to complete these prior works. The TSolution One Surgical System® (Think Surgical Inc., California, USA) includes a surgical planning workstation (named TPLAN®) that would be interesting to assess for itself and to consolidate the field. Indeed, on one hand, evaluating this other option could confirm the reliability ranges previously published and therefore suggest that reliability is rather universal. On the other hand, it could indicate variations in reliability data and possibly highlight elements that could affect the reliability.

The objectives of the study were to characterize the intra- and inter-operator reliability of the TPLAN® surgical planning workstation for implant size selection and implant placements.

Materials and methods

Three orthopedic surgeons with prior experience in 3D surgical planning participated in this IRB-approved study after completing the standard training dispensed by the planning software manufacturer. At the beginning of the study, the surgeons agreed on the surgical planning objectives, which were to have a neutral mechanical axis, a femoral axial rotation based on the transepicondylar axis and a tibial slope restoring the bone morphology with a cap at 5°. This study used exclusively “Unity Posterior Stabilized Femoral” and “Unity Tibial” implants (Corin, Cirencester, UK).

Thirty CT scans of de-identified knees with osteoarthritis were uploaded and processed in TPLAN®. A sample size of 30 knees was chosen, according to the statistical methods described by Walter et al. [12], to detect expected reliability of 0.8 (ρ0), considering a minimal level of reliability of 0.6 (ρ1), α of 0.05 and β of 0.2. For each knee, a case planner from Think Surgical Inc. segmented the bones and pre-planned the TKA using TPLAN® according to the planning objectives. The pre-planning consisted in identifying bony landmarks, selecting implant sizes, and placing the implants relative to the 3D bone models. The surgical planning workstation provided assistance for achieving certain objectives, such as positioning the implant in a neutral mechanical axis and parallel to the transepicondylar axis, through coronal and transverse alignment presets.

After the pre-planning, each surgeon reviewed the 30 cases three times (Fig. 1). The orders in which the surgeons reviewed their 90 cases were randomized, and there was a minimum of one week between reviews of the same knee. The surgeons were provided with a series of 90 cases without indication of which cases were from the same knees. In addition, no feedback was provided to the surgeons during the review of the 90 cases. The review process included two steps. First, the surgeons determined the implant sizes they thought would be the most adapted, independently of the sizes selected during the pre-planning and reported these sizes in a chart. Then, they examined and, if necessary, modified the pre-planning according to the planning objectives. For this, the surgeons could modify the identification of the bony landmarks and the position and orientation of the implants, but not the implant sizes. The use of predetermined implant sizes excluded the possibility of having knees planned with different implant sizes which would have biased the analysis of the implant position and orientation reliability.

Fig. 1 Study chart for one knee (30 knees in total)

Reliability analysis

The implant position and orientation were described with respect to the anatomical frames [13]. The position was measured along the anterior-posterior, proximal-distal and medial-lateral axes and the orientation using angles in the sagittal, frontal and transverse planes. The reliability was not assessed for the femur and tibia in the coronal plane and for the femur in the transverse plane because these degrees-of-freedom were not at the discretion of the surgeons but fixed by the planning objectives and forced by the planning software.

The reliability in implant sizes and implant placements were described with Intraclass Correlation Coefficient (ICC) and Standard Error of Measurement (SEM). ICC was used to estimate the degree of reliability, while SEM was reported to quantify the magnitude of variations. The intra-operator reliability was evaluated independently for each surgeon and degree-of-freedom based on the three measures for the 30 knees. For the inter-operator reliability, a bootstrap method was used consisting of random selections of one measure for each surgeon (out of the three). The interpretation guidelines of Landis and Koch were used, with ICC between 0.0 and 0.2 indicating slight reliability, between 0.21 and 0.4 indicating fair reliability, between 0.41 and 0.6 indicating moderate reliability, between 0.61 and 0.8 indicating substantial reliability, and between 0.81 and 1.0 indicating almost perfect reliability [14]. For the implant size selection, the reliability was also assessed using the percentage agreement for exact size, as well as for each size unit of disagreement. Data processing and statistical analysis were done with Matlab (Mathworks, Natick, MA).

Results

Analyzing the surgeons individually indicated that they selected the same implant size 76.7–90.0% of the time for the femur and 73.3–83.3% of the time for the tibia. When considering a one size difference, the percentage increased to 100% for the three surgeons and both bones, meaning that the size selection never differed by more than one unit. The results were similar inter-operator, with a selection of the same implant size 79.6% of the time for the femur and 67.1% of the time for the tibia, and an increase to 100% when considering one size difference. All the implant size ICC were considered almost perfect (between 0.97 and 0.99), with SEM between 0.15 and 0.3 unit (Table 1).

Table 1 Intra- and inter-operator reliability (n = 30 knees)

		Femur	Tibia	
	Intra-opertor
Surgeon 1	Intra-opertor
Surgeon 2	Intra-opertor
Surgeon 3	Inter-opertator	Intra-opertor
Surgeon 1	Intra-opertor
Surgeon 2	Intra-opertor
Surgeon 3	Inter-opertator	
Implant size	ICC (CI)	0.99 (0.98–0.99)	0.97 (0.95–0.99)	0.99 (0.99-1.00)	0.98 (0.98–0.98)	0.98 (0.97–0.99)	0.98 (0.96–0.99)	0.99 (0.98–0.99)	0.98 (0.98–0.98)	
	SEM, size unit	0.18	0.28	0.15	0.25	0.26	0.30	0.21	0.30	
Position										
Anterior-posterior	ICC (CI)	1.00 (0.99-1.00)	0.90 (0.81–0.95)	0.98 (0.95–0.99)	0.86 (0.85–0.86)	0.98 (0.96–0.99)	0.94 (0.89–0.98)	0.97 (0.94–0.99)	0.93 (0.93–0.93)	
	SEM, mm	0.26	0.90	0.57	1.40	0.37	0.59	0.42	0.59	
Proximal-distal	ICC (CI)	0.99 (0.98-1.00)	0.84 (0.71–0.92)	0.93 (0.86–0.97)	0.85 (0.85–0.86)	0.99 (0.98–0.99)	0.87 (0.75–0.94)	1.00 (1.00–1.00)	0.92 (0.92–0.92)	
	SEM, mm	0.15	0.87	0.44	0.68	0.14	0.44	0.00	0.42	
Lateral-medial	ICC (CI)	0.92 (0.84–0.96)	0.84 (0.71–0.92)	0.81 (0.67–0.91)	0.82 (0.82–0.82)	0.98 (0.95–0.99)	0.96 (0.92–0.98)	1.00 (0.99-1.00)	0.95 (0.95–0.95)	
	SEM, mm	0.41	0.57	0.65	0.56	0.39	0.38	0.12	0.40	
Orientation										
Transverse plane	ICC (CI)	n/a	n/a	n/a	n/a	0.98 (0.95–0.99)	0.91 (0.81–0.96)	0.98 (0.95–0.99)	0.91 (0.91–0.91)	
	SEM, °	n/a	n/a	n/a	n/a	1.12	1.59	0.90	1.74	
Sagittal plane	ICC (CI)	0.99 (0.97–0.99)	0.76 (0.59–0.88)	0.94 (0.88–0.97)	0.60 (0.60–0.60)	0.44 (0.20–0.67)	0.12 (-0.13-0.44)	1.00 (1.00–1.00)	0.03 (0.03–0.03)	
	SEM, °	0.18	1.23	0.36	1.25	0.81	1.49	0.01	1.73	
ICC: Interclass correlation coefficient; CI: 95% Confidence interval; SEM: Standard error of measurement

The intra-operator reliability for the femur and tibia were almost perfect (ICC between 0.81 and 1.00), except in the femoral sagittal plane, where it was substantial for one surgeon (ICC of 0.76), and in the tibial sagittal plane, where it was moderate (ICC of 0.44) and slight (ICC of 0.12) for two surgeons. The intra-operator SEM were below 1 mm or 1°, except for one surgeon in the femoral sagittal plane (SEM of 1.23°), tibial transverse plane (1.59°) and tibial sagittal plane (1.49°) and for another surgeon in the tibial transverse plane (1.12°).

The inter-operator reliability for the femur and tibia were almost perfect (ICC between 0.83 and 0.99), except for the femoral sagittal plane, where it was moderate (ICC of 0.60), and the tibial sagittal plane, where it was slight (ICC of 0.03). The inter-operator SEM were below 1 mm or 1°, except for the femur along the anterior-posterior axis and in the sagittal plane (SEM of 1.40 mm and 1.25°, respectively) and for the tibia in the transverse and sagittal planes (SEM of 1.74° and 1.73°, respectively).

Discussion

This study showed a high level of agreement in implant size selection, with the same size selection at least 67% of the time and differences never exceeding one size. These results are in agreement with prior studies using other planning methods, where same size selection was reported to vary between 44.3% and 66.7% [10] and ICC ranged from 0.84 to 0.99 [11]. Altogether, this is encouraging as inappropriate implant size has been related to various complications and inferior clinical outcomes. Specifically, oversizing of the femoral implants has been associated with increase in pain, decrease in knee function and lower postoperative flexion [15, 16]. Regarding the tibial implants, oversizing has been associated with higher risks of inferior knee injury, increased pain and inferior functional outcomes [15, 17, 18], while undersizing has been related to an increased rate of tibial implant loosening and prosthetic failure [19]. The results are also encouraging regarding costs and operating room efficiency as several studies have reported larger burden when the differences in implant sizes varies by more than one size between the planning and the surgery [20, 21].

Both intra- and inter-operator implant placements demonstrated almost perfect reliability (ICC above 0.81) and low variation among plannings (SEM below 1 mm or 1°) for all degrees-of-freedom, except for four that are discussed hereafter. Along the femoral anterior-posterior axis, the ICC was lower and the SEM larger among surgeons than within surgeons, suggesting that the surgeons remained consistent over time, but understood the implant placements objectives differently. In the tibial transverse plane and in the femoral and tibial sagittal planes, the reliability was lower both intra- and inter-operator, suggesting less specific definitions for the placements of the implants in these degrees-of-freedom. These observations question the possibility and relevance of adding new features in planning software to assist the operator. Such additions could indeed improve the reliability particularly in the four degrees-of-freedom mentioned above. This being said, it is important to note that the variations among plannings remained relatively low both intra- and inter-operator, with SEM values below 1.3 mm or 1.7°. Consequently, to push the interpretation further and spot effective sources of improvement, additional research on the clinical impact of the planning reliability appears necessary.

Compared to the reliability data in two prior TKA publications, the present study reported at least comparable performance. Miura et al. found almost perfect reliability intra- and inter-operator in the femoral coronal plane (ICC of 0.81 and 0.89, respectively), but only moderate to substantial reliability in the femoral transverse plane (ICC of 0.46 and 0.62, respectively) [10]. In another work, Schoenmakers et al. reported almost perfect inter-operator reliability (ICC range from 0.92 to 1.00) for six out of twelve degrees-of-freedom, including the femur along all axes and in the transverse plane, and the tibia in the transverse and sagittal planes [11]. These authors also reported almost perfect intra-operator reliability (ICC range from 0.90 to 1.00) for seven out of twelve degrees-of-freedom, including the femur along all axes and in the transverse plane, and the tibia along the proximal-distal axis and in the transverse and sagittal planes. Comparing the reliability in the three studies reveals some disparities, which could be caused by several factors, including the software, the assistance in implant placements, the imaging modality, the operator, and even the method of assessment. Additional research is thus necessary to fully understand the underlying factors contributing to the differences among studies and manage them at best.

For a better perception of the implications of the planning reliability, it is interesting to mention that the robotic system coupled to the planning software assessed in this study has been reported to cut the bones with root-mean-square errors below 1.8 mm or 1° in the six degrees-of-freedom for both the femur and the tibia [22]. Consequently, the reliability of the implant placements appeared to be adequate with regard to the accuracy of the bone cuts.

This study has some limitations. First, until further research with other types of implants and 3D preoperative planning software has been conducted, the generalizability of the findings remains unknown. Additional research will also be needed to evaluate the impact of the CT scan and the pre-planning of the reliability. Second, it happened that the surgeons had to plan the surgery with implants they thought were not of the ideal size, which could have contributed to lower the reliability. In this regard, it is important to mention that less than a third of the plannings were done with an implant size differing from what the surgeons would have selected and never with an implant differing by more than one size.

Conclusion

This study reported high intra- and inter-operator levels of reliability for implant size selection and implant placements in a majority of the degrees-of-freedom. The lower reliability in implant placements observed in four degrees-of-freedom suggested both variations in the understanding of the planning objectives and a lack of specific definitions for the placements of the implants. This encourages further works to propose more precise means to describe the objectives of the surgical planning as well as the consideration of additional features in planning software to assist the operators, particularly in the four degrees-of-freedom with lower reliability. This being said, it should be noted that the maximum SEM of 1.3 mm or 1.7° remained relatively small and that further research is needed to determine the impact of the planning reliability on the clinical outcomes.

Acknowledgements

BMJ and JF supervised this study and should be considered as last authors.

Author contributions

According to the “Uniform requirements for manuscripts submitted to biomedical journals”, all authors have contributed significantly to the study. All authors have approved submission of the manuscript.

Funding

This research was partially funded by Think Surgical Inc.

Open access funding provided by University of Lausanne

Data availability

Not applicable.

Declarations

Ethical approval

All procedures were done in accordance with the local ethics committee.

Conflict of interest

The study was designed in consultation with Think Surgical Inc. and partially funded by Think Surgical. Data acquisition and analysis, as well as reporting were done independently by the authors. To avoid public disclosure of confidential information, Think Surgical Inc. had the opportunity to review the manuscript before its submission for publication.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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References

1. Sloan M Premkumar A Sheth NP Projected Volume of Primary Total Joint Arthroplasty in the U.S., 2014 to 2030 J Bone Joint Surg Am 2018 100 1455 1460 10.2106/JBJS.17.01617 30180053
Sloan M, Premkumar A, Sheth NP (2018) Projected Volume of Primary Total Joint Arthroplasty in the U.S., 2014 to 2030. J Bone Joint Surg Am 100:1455–1460. 10.2106/JBJS.17.0161730180053
2. Bourne RB Chesworth BM Davis AM Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 2010 468 57 63 10.1007/s11999-009-1119-9 19844772
Bourne RB, Chesworth BM, Davis AM et al (2010) Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res 468:57–6319844772
3. Halawi MJ Jongbloed W Baron S Patient dissatisfaction after primary total joint arthroplasty: the patient perspective J Arthroplasty 2019 34 1093 1096 10.1016/j.arth.2019.01.075 30799270
Halawi MJ, Jongbloed W, Baron S et al (2019) Patient dissatisfaction after primary total joint arthroplasty: the patient perspective. J Arthroplasty 34:1093–109630799270
4. Ritter MA Faris PM Keating EM Meding JB Postopera-tive alignment of total knee replacement. Its effect on survival Clin Orthop Relat Res 1994 299 153 156 10.1097/00003086-199402000-00021
Ritter MA, Faris PM, Keating EM, Meding JB (1994) Postopera-tive alignment of total knee replacement. Its effect on survival. Clin Orthop Relat Res 299:153–156
5. Jacofsky DJ Allen M Robotics in Arthroplasty: a Comprehensive Review J Arthroplasty 2016 31 2353 2363 10.1016/J.ARTH.2016.05.026 27325369
Jacofsky DJ, Allen M (2016) Robotics in Arthroplasty: a Comprehensive Review. J Arthroplasty 31:2353–2363. 10.1016/J.ARTH.2016.05.02627325369
6. Bautista M Manrique J Hozack WJ Robotics in total knee arthroplasty J Knee Surg 2019 32 600 606 10.1055/s-0039-1681053 30822790
Bautista M, Manrique J, Hozack WJ (2019) Robotics in total knee arthroplasty. J Knee Surg 32:600–606. 10.1055/s-0039-168105330822790
7. Ren Y Cao S Wu J Efficacy and reliability of active robotic-assisted total knee arthroplasty compared with conventional total knee arthroplasty: a systematic review and meta-analysis Postgrad Med J 2019 95 125 133 10.1136/postgradmedj-2018-136190 30808721
Ren Y, Cao S, Wu J et al (2019) Efficacy and reliability of active robotic-assisted total knee arthroplasty compared with conventional total knee arthroplasty: a systematic review and meta-analysis. Postgrad Med J 95:125–13330808721
8. Shatrov J Parker D Computer and robotic – assisted total knee arthroplasty: a review of outcomes J Exp Orthop 2020 7 1 15 10.1186/S40634-020-00278-Y 31900597
Shatrov J, Parker D (2020) Computer and robotic – assisted total knee arthroplasty: a review of outcomes. J Exp Orthop 7:1–15. 10.1186/S40634-020-00278-Y31900597
9. Thienpont E Schwab PE Fennema P Efficacy of Patient-Specific Instruments in total knee arthroplasty: a systematic review and Meta-analysis J Bone Joint Surg Am 2017 99 521 530 10.2106/JBJS.16.00496 28291186
Thienpont E, Schwab PE, Fennema P (2017) Efficacy of Patient-Specific Instruments in total knee arthroplasty: a systematic review and Meta-analysis. J Bone Joint Surg Am 99:521–530. 10.2106/JBJS.16.0049628291186
10. Miura M Hagiwara S Nakamura J Interobserver and Intraobserver reliability of computed tomography–based three-Dimensional Preoperative Planning for primary total knee arthroplasty J Arthroplasty 2018 33 1572 1578 10.1016/j.arth.2017.12.035 29352686
Miura M, Hagiwara S, Nakamura J et al (2018) Interobserver and Intraobserver reliability of computed tomography–based three-Dimensional Preoperative Planning for primary total knee arthroplasty. J Arthroplasty 33:1572–1578. 10.1016/j.arth.2017.12.03529352686
11. Schoenmakers DAL Theeuwen DMJ Schotanus MGM High intra- and inter-observer reliability of planning implant size in MRI-based patient-specific instrumentation for total knee arthroplasty Knee Surg Sports Traumatol Arthrosc 2021 29 573 578 10.1007/S00167-020-05946-1 32232539
Schoenmakers DAL, Theeuwen DMJ, Schotanus MGM et al (2021) High intra- and inter-observer reliability of planning implant size in MRI-based patient-specific instrumentation for total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 29:573–578. 10.1007/S00167-020-05946-132232539
12. Walter SD Eliasziw M Donner A Sample size and optimal designs for reliability studies Stat Med 1998 17 101 110 10.1002/(SICI)1097-0258(19980115)17:1<101::AID-SIM727>3.0.CO;2-E 9463853
Walter SD, Eliasziw M, Donner A (1998) Sample size and optimal designs for reliability studies. Stat Med 17:101–1109463853
13. Victor J Van Doninck D Labey L How precise can bony landmarks be determined on a CT scan of the knee? Knee 2009 16 358 365 10.1016/j.knee.2009.01.001 19195896
Victor J, Van Doninck D, Labey L et al (2009) How precise can bony landmarks be determined on a CT scan of the knee? Knee 16:358–36519195896
14. Landis JR Koch GG The measurement of Observer Agreement for Categorical Data Biometrics 1977 33 159 10.2307/2529310 843571
Landis JR, Koch GG (1977) The measurement of Observer Agreement for Categorical Data. Biometrics 33:159. 10.2307/2529310843571
15. Bonnin MP Schmidt A Basiglini L Mediolateral oversizing influences pain, function, and flexion after TKA Knee Surg Sports Traumatol Arthrosc 2013 21 2314 2324 10.1007/S00167-013-2443-X 23404515
Bonnin MP, Schmidt A, Basiglini L et al (2013) Mediolateral oversizing influences pain, function, and flexion after TKA. Knee Surg Sports Traumatol Arthrosc 21:2314–2324. 10.1007/S00167-013-2443-X23404515
16. Mahoney OM Kinsey T Overhang of the femoral component in total knee arthroplasty: risk factors and clinical consequences J Bone Joint Surg Am 2010 92 1115 1121 10.2106/JBJS.H.00434 20439656
Mahoney OM, Kinsey T (2010) Overhang of the femoral component in total knee arthroplasty: risk factors and clinical consequences. J Bone Joint Surg Am 92:1115–1121. 10.2106/JBJS.H.0043420439656
17. Nielsen CS Nebergall A Huddleston J Medial overhang of the tibial component is Associated with higher risk of inferior knee Injury and Osteoarthritis Outcome score Pain after knee replacement J Arthroplasty 2018 33 1394 1398 10.1016/J.ARTH.2017.12.027 29452971
Nielsen CS, Nebergall A, Huddleston J et al (2018) Medial overhang of the tibial component is Associated with higher risk of inferior knee Injury and Osteoarthritis Outcome score Pain after knee replacement. J Arthroplasty 33:1394–1398. 10.1016/J.ARTH.2017.12.02729452971
18. Bonnin MP Saffarini M Shepherd D Oversizing the tibial component in TKAs: incidence, consequences and risk factors Knee Surg Sports Traumatol Arthrosc 2016 24 2532 2540 10.1007/S00167-015-3512-0 25605560
Bonnin MP, Saffarini M, Shepherd D et al (2016) Oversizing the tibial component in TKAs: incidence, consequences and risk factors. Knee Surg Sports Traumatol Arthrosc 24:2532–2540. 10.1007/S00167-015-3512-025605560
19. Berend ME Ritter MA Hyldahl HC Implant migration and failure in total knee arthroplasty is related to body mass index and tibial component size J Arthroplasty 2008 23 104 109 10.1016/J.ARTH.2008.05.020 18722310
Berend ME, Ritter MA, Hyldahl HC et al (2008) Implant migration and failure in total knee arthroplasty is related to body mass index and tibial component size. J Arthroplasty 23:104–109. 10.1016/J.ARTH.2008.05.02018722310
20. Schotanus MGM Schoenmakers DAL Sollie R Kort NP Patient-specific instruments for total knee arthroplasty can accurately predict the component size as used peroperative Knee Surg Sports Traumatol Arthrosc 2017 25 3844 3848 10.1007/S00167-016-4345-1 27709239
Schotanus MGM, Schoenmakers DAL, Sollie R, Kort NP (2017) Patient-specific instruments for total knee arthroplasty can accurately predict the component size as used peroperative. Knee Surg Sports Traumatol Arthrosc 25:3844–3848. 10.1007/S00167-016-4345-127709239
21. McLawhorn AS Carroll KM Blevins JL Template-Directed Instrumentation reduces cost and Improves Efficiency for Total Knee Arthroplasty: an Economic Decision Analysis and pilot study J Arthroplasty 2015 30 1699 1704 10.1016/J.ARTH.2015.04.043 26021908
McLawhorn AS, Carroll KM, Blevins JL et al (2015) Template-Directed Instrumentation reduces cost and Improves Efficiency for Total Knee Arthroplasty: an Economic Decision Analysis and pilot study. J Arthroplasty 30:1699–1704. 10.1016/J.ARTH.2015.04.04326021908
22. Cosendey K Stanovici J Mahlouly J Bone cuts accuracy of a system for total knee arthroplasty including an active robotic arm J Clin Med 2021 10 3714 10.3390/JCM10163714 34442008
Cosendey K, Stanovici J, Mahlouly J et al (2021) Bone cuts accuracy of a system for total knee arthroplasty including an active robotic arm. J Clin Med 10:3714. 10.3390/JCM1016371434442008
